Amish burn ointment and burdock leaf dressings: assessments of antimicrobial and cytotoxic activities.

Amish burn wound ointment (ABO) contains honey, lanolin, oils, glycerin, bees wax, and other natural additives. Although there are many anecdotal reports that this ointment covered with a burdock leaf (BL) dressing promotes burn wound healing, little scientific testing of this treatment has occurred. The goal of this study was to evaluate in vitro some of the components of this treatment modality for antimicrobial and cytotoxic activities. The ABO was tested for sterility using standard microbiological techniques. Because of the semisolid, lipid-based nature of the salve, the at-use product could not be tested in bioassays. Samples of BL and the dry ingredients (DI) used in the ointment were provided by the Amish vendor. Aqueous extracts of the DI and of the BL were prepared and freeze dried. The freeze-dried extracts were reconstituted, filtered, and tested separately on keratinocyte and fibroblast cell cultures for cytotoxicity (growth inhibition assay) and against a panel of susceptible and resistant microbes for antimicrobial activity (Nathan's agar-well diffusion assay) in a series of concentrations (% wt/vol). Neither DI nor BL extracts demonstrated antimicrobial activity against any of organisms tested. The DI extract inhibited growth of both keratinocytes and fibroblasts at the 0.1% concentration. The 0.1 and 0.03% concentrations of the BL extract were cytotoxic to both keratinocytes and fibroblasts. Although tests for microbial growth from the at-use preparation of the ABO were negative, extracts of the DI and BL did not demonstrate any antimicrobial activity. Additionally, both extracts inhibited the growth of skin cells in vitro at higher concentrations. These results suggest caution in the use of ABO and BL dressings if there is more than a minimal risk of complications from the burn injury.